Systems for obtaining real-time spatial information on objects placed within a living body are often utilized for the monitoring of invasive treatments. The monitoring sometimes involves registration of the spatial information with medical images taken by another imaging modality. For example, U.S. Patent Application Publication 2008/0085042 describes a method for imaging that includes receiving a first three-dimensional (3D) image of a vicinity of an organ within a body of a subject and creating a geometrical model of a tubular structure in the first 3D image in the vicinity of the organ. An invasive probe is inserted into the organ, and a second 3D image containing the organ is captured using the invasive probe. One or more points are located on a surface of the tubular structure using the invasive probe, and the second 3D image is registered with the first 3D image by matching the one or more points to the geometrical model.
As another example, U.S. Patent Application Publication 2007/0225593 describes a device for enhancing visualization of an esophagus when imaged by a visualization system. The device comprises a structure including material that is clearly visible when imaged by the visualization system. The structure is arranged, when inserted into the esophagus, to expand so as to conform to an inner surface of the esophagus in order to enhance a visualization quality of the surface when imaged by the visualization system. A cord attached to the structure is arranged to extend out of the esophagus so as to assist a removal of the device from the esophagus.
U.S. Pat. No. 8,456,182 describes a method that includes positioning body-electrodes in galvanic contact with a body of a patient and positioning a mapping-tool, having a mapping-electrode, in a plurality of regions in the body. The method further includes tracking the mapping-tool at different positions in each of the regions using a location-measuring system, and for each region, generating a respective set of calibration-currents between the body-electrodes and the mapping-electrode at the different positions in the region. A respective relation is derived for each region between the respective set of the calibration-currents and the different positions, and is used in determining the location of an investigation-tool in response to the different respective relations and investigation-tool-currents.
U.S. Patent Application Publication 2006/0116576 describes systems and method for navigating a medical probe relative to the heart. A mark (such as a point or a line), representing an anatomical region of interest (such as tissue targeted for treatment or tissue not targeted for treatment) is displayed on a representation of the anatomical body. The positions of the medical probe and the mark are determined within a three-dimensional coordinate system, and the proximity between the medical probe and the mark determined based on these positions. This proximity can then be indicated to a user, e.g., using graphics, text, or audible sounds.
U.S. Patent Application Publication 2007/0049817 describes systems and methods for registering maps with images, involving segmentation of three-dimensional images and registration of images with an electro-anatomical map using physiological or functional information in the maps and the images, rather than using only location information. A typical application of the invention involves registration of an electro-anatomical map of the heart with a pre-acquired or real-time three-dimensional image. Features such as scar tissue in the heart, which typically exhibits lower voltage than healthy tissue in the electro-anatomical map, can be localized and accurately delineated on the three-dimensional image and map.